Fluid operated controller



Dec. 3, 1940. A. E. KROGH FLUID OPERATED CONTROLLER Filed May 22, 1937 3 Sheets-Sheet l m m m N I A TTORNEY H G 0 R K E BY QWQQQ Dec. 3, 1940.

A. E, KROGH FLUID OPERATED CONTROLLER Filed May 22, 1937 3 Sheets-Sheet 2 [N V EN TOR. ANER E. KROGH A TTORNEY Dec. 3, 1940. A. E. KROGH FLUID OPERATED CONTROLLER Filed Ma? 22, 1937 5 Sheets-Sheet 5 i 'ANKER & KROGH ATTORNEY Patented Dec. 3, 1940 UNITED STATES FLUID OPERATED CONTROLLER Anker E. Krogh, Philadelphia, Pa., asslgnor to, The Brown Instrument Company, Philadelphia, Pa., a. corporation of Pennsylvania Application May 22, 1937, Serial No. 144,287

4 Claims.

The general object of the present invention is to provide improved means for creating an air pressure control force varied by and in accordance with changes in a controlling fluid pressure,

5 and particularly devised and adapted for use where the controlling pressure is small, and varies through a relatively small range, as does the pressure in the combustion chamber of an openhearth furnace, for example. The present inm vention is well adapted for controlling the pressure in such a furnace chamber, but is not restricted to such use. Y

A preferred embodiment of the present invention comprises an instrument in which air controller instrument mechanism, preferably of one or another existing commercial type, is combined with simple and efiective means for adjusting the controlling element of said mechanism in suitably close and accurate correspondence with the small changes in a furnace chamber or other small controlling pressure, and so as to practically eliminate interference due to friction or loss motion in the action on said controlling element, of said means, the latter being of a character to respond to, and to be actuated by a force, transmitted to the instrument from the furnace or other distant source of controlling pressure, and varying in accordance with changes in said pressure.

In one advantageous form of the present invention, the air instrument actuating means responsive to the force transmitted to the instrument, is the receiver element of a so-called inductance bridge including a transmitter element which is adjusted by a pressure gauge which may be located adjacent the furnace chamber or other 'soure of the controlling pressure. In another desirable form of the present invention, the said instrument actuating means is a pressure gauge 40 including a bell which depends into sealing liquid and is adjusted to difierent vertical positions by variations in the controlling pressure which is transmitted to said gauge. In the one form, the vertically movable armature of the inductance 5 bridge receiver is suspended from a lever connected by a linkage substantially free from lost motion or frictional resistance, to the controlling element of the air controller mechanism and in the second above mentioned form, the bell mem- 50 her of the gauge is suspended from a lever connected, as is the first mentioned lever, to said controlling element.

The various features of novelty which characterize my invention are pointed outwith pargs ticularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, however, its advantages, and specific objects attained with it, reference should be had to the accompanying drawings and descriptive matter in which I have illus- 5 trated and described preferred embodiments of the. present invention.

Of the drawings:

Fig. 1 is a somewhat diagrammatic representation of an open-hearth furnace and mechanism 10 including a pressure responsive air controller instrument, for controlling the pressure in the combustion chamber of the furnace;

Fig. 2 is an elevation with parts broken away and in. section of a pressure responsive air con- 15 troller embodying essential features of, but differing somewhat from the instrument shown in Fig. 1;

Fig. 3 is an elevation of a pressure responsive control instrument including pressure responsive 20 actuating means for the air controller mechanism different in type from the means shown in Figs.

1 and 2; and

Fig. 4 is a perspective view of a portion of the instrument mechanism shown in Fig. 3; .25

In Fig. l, I have illustrated the use of one preferred form of the present invention, in controlling the pressure in the combustion and heating chamber a of a furnace A, shown as of the openhearth regenerative melting furnace type. In the 30 furnace illustrated by way of example in Fig. l, preheated combustion air is passed alternately to the opposite ends of the chamber a, by corresponding regenerators A and a, each of which is adapted to be connected at its end remote from .35 the chamber a, through conduits and ports A and a alternately to a chimney or stack (not shown), or to a combustion air inlet A which may be variably throttled by a damper B. When the furnace is receiving preheated air at one end 40 or the other, fuel, as i'uel oil, is also supplied to that end of the chamber through a corresponding burner pipe A or a.

In Fig. l, the pressure in the chamber a is transmitted through a pipe C,communicatingwith the chamber A through branches 0' opening to the chamber through its roof, to a device 43. The latter includes a pressure gauge of known type, comprising a container for a body of sealing liquid D, and a vertically movable bell D dipping into the sealing liquid and surrounding the upper portion of a vertical extension C of the pipe C, which has-its open upper end suitably above the sealing liquid D. The bell D is suspended i'rom one arm of a horizontally disposed I lever D fulcrumed at D, intermediate its ends, and from the second arm of which is suspended the armature E of the transmitter element of an inductance bridge, of the character disclosed in the Harrison Patent No. 1,743,853.

' The said transmitter element comprises two end to end vertically disposed coils E and E in which the armature E is axially movable. As shown, the transmitter element is located in a cylindrical shell E within the housing or casing of the device D, and open at its upper end, and conveniently arranged with its closed lower end extending down into the sealing liquid D and resting on the bottom of said housing. The portion of the housing interior above the sealing liquid, is in free communication with the atmosphere, as by means of a port D so that the pressure acting on the unsubmerged outer surface of the bell D is that of the atmosphere. The lever D carries an index or pointer D cooperating with a scale D to show the pressure in the chamber a.

The receiver element of the inductance bridge is mounted within the casing of the air controller instrument F, and comprises an armature e, and coils e and e'-, which may be formed and relatively disposed, exactly like the corresponding parts E, and E and E of the transmitter. The remote ends of the coils E and E are connected by br-idge conductors 3 and 4, respectively, to the remote ends of the coils e and c The adjacent ends of the coils E and E are connected by bridge conductor 5, to the adjacent ends of the coils e and e*. The bridge is energized by alternate current supply conductors I and 2 connected to the conductors 3 and 4 respectively. The winding direction is the same in the coils E and E and the coils e' and c With the inductance bridge arranged and energized as described, an up movement, for example, of the transmitter armature E, increases the impedance of the coil E, and decreases: the impedance of the coil E Those impedance changes result in a current flow in the conductor 5, and a consequent increase of current flow through the coil e relative to the current flow through the coil e which, when the armature e is free to move as it is in the instrument F, causes that armature to move upward until the relative increase in the impedance of the coil e relative to that of the coil e makes the impedance ratio of the coils e and e equal to the impedance ratio of the coils E and E This restores the balanced condition of the bridge. Conversely, down movement of the armature E causes a corresponding'down movement of the armature e. The position of the receiver armature e is thus dependent upon, and fixed by the position of the armature E, for all positions of the latter, and hence for all positions of the bell member D of the device D.

As will be apparent without further explanation, with proper calibration and adjustment of the device D, including the maintenance of the proper amount of sealing liquid D' therein, the vertical position of the bell D and hence of the armature E will be in precise and definite correspondence at all times with the differential between the pressure of the atmosphere and the pressure in the furnace chamber a.

The instrument F comprises air controller mechanism of a known type, and including a flapper valve F biased for movement toward the bleed vent or orifice formed by the open upper end 02a pipe F", which has an upper end portion horizontally disposed and transverse to the flapper valve F'. The latter is held at varying distances from the open end of the pipe F in accordance with the different vertical positions of the receiver armature e. Changes in position of the armature e, efiect corresponding ad- Justments of the flapper valve F through a lever F having its fulcrum at F and comprising a horizontally disposed arm from which the armature e is suspended. The lever F is connected by a link F to one end of an oscillating element or lever F pivoted at' F". The oscillatory movements given to the element F, in correspondence with the oscillatory movements of the lever F effect adjustments of the flapper valve F through a link F having its upper end pivoted at F to the element F, and pivotally connected at its lower end to a lever F which is pivotally supported at F and carries a pin F engaging the flapper valve F. The operating means for the flapper valve F is preferably in gravitational balance, and to permit that balance to be established, the lever F is shown as provided with an adjustable counterweight F Through the lever F and the linkage connection between the latter and the lever F down and up movements of the armature e, produce clockwise and counterclockwise movements, respectively, of the lever F On a clockwise movement of the lever F the pin F moves the flapper F away from, and reduces its throttling efiect on, the bleeder orifice end of the pipe F and on a counterclock adjustment of the lever F the pin F permits the flapper F to move under its bias force closer to the bleeder orifice end of the pipe F whereby its throttling effect on the bleed flow through the pipe 1" is increased.

As" the flapper valve F is permitted to approach, or is moved away from the bleed orifice end of the pipe F the pressure in the latter is correspondingly varied as a result of the fact that the pipe F communicates through a restricted orifice G with an air supply pipe G, receiving compressed air ata suitable, and approximately constant pressure, from a suitable source of such air.

The pressure variations in the pipe F produce corresponding pressure variations in a control pressure pipe H, through which, in the arrangement shown in Fig. 1, the instrument F controls the operation of a regulator I by which the furnace air inlet damper B is adjusted as required to hold the pressure in the chamber a at its determined value. In the instrument F shown in Fig. 1, the pressure in the pipe F is not directly transmitted to the pipe H, but controls a pilot valve mechanism by which air is passed to the pipe H from the supply pipe G or is permitted to exhaust from the pipe H/as required to maintain a constant proportion fbetween the pressure in the pipe F and the pressure in the pipe H. v

The pilot valve mechanism of the instrument F comprises a chamber F in a portion of the instrument housing. The pipe H is connected to chamber F and the latter has an air vent,,

formed by the bore of a vent nozzle F extending into the chamber F with its open end facing and spaced away from the open end of a nozzle branch G from the air supply pipe G. A pivoted valve member F extends between the open ends of the nozzles G and F so. that as I it moves away from either and approaches the other nozzle, its throttling eiiect on flow through those nozzles-is respectivelydecreased and increased. The valve member F is given its movements by its connection to a diaphragm F The latter forms a movable wall for a chamber F". with which the pipe 1 is in communication. As

will be apparent, with the described arrangement,

Fig. '1, the pilot valve mechanism employed or-' dinarily is of a character such that the pressure in its chamber corresponding to the chamber F is greater than the pressure in the pipe F at all times, though proportional thereto.

The regulator I shown in Fig. 1, gives corrective closing and opening adjustments to the air inlet damper B. on increases and decreases, respectively in the pressure in the chamber a, and corresponding increases and decreases in the control pressure transmitted to the regulator I through the-pipe H from the instrument F. As will be apparent, the regulator I can take various forms. The particular regulator form illustrated in Fig. 1 is of the servo-motor type, including a working cylinder I and a piston P working in that cylinder and having its stem connected to the operating arm B of the damper B. The opposite ends of the cylinder I' are connected by pipes I and I to ports in a valve casing 1 including an automatic valve'mecha nism 1 adjusted, as a result of variations in the control pressure in pipe H, to connect the pipe I or I to a motive fluid supply pipe I" on an increase or decrease, respectively, in the control pressure. The adjustment of valve mechanism thus connecting pipe I or I to pipe 1'', opens the pipe I or F, respectively, to exhaust through the interior of the valve casing, which is provided with an exhaust vent I. In the diagrammatic showing of Fig. l, the valve casing I is shown a larger scale than that of the cylinder I".

The actuating means for the valve mechanism I includes a bellows element I to the interior of which the control pressure pipe H opens. The movable end wall of the bellows I acts on the valve mechanism 1 through a rod 1 An increase or decrease in the pressure transmitted by the pipe H to bellows I elongates or contracts the latter, and thereby adjusts the valve mechanism I to connect the pipe I or the pipe I to the motive fluid supply pipe I", and thus starts piston 1* into movement down or up. The piston motion thus instituted continues until that movement effects a corresponding readjustment of the valve mechanism 1, through means comprising a cross-head or arm Ilcarried by the stem of the piston I and carrying a rack bar 1 The latter is parallel to the piston stem and extends into the casing I and has its gear teeth in mesh with the teeth of a spur gear I journalled in the casing I and carrying a cam 1 As the latter is rotated on a down movement of the rack bar I it gives an oscillatory movement to a rocking element I and thereby gives a down movement to a member I", the upper end of which is engaged by an arm portion I of the rocking elementl The member I" is coaxial with the rod I, and forms a movable abutment for one end of a spring I acting between the abutment member I" and the movable end wall of the bellows I". The down movement of the abutment I" thus eilected, continues until the tension of the spring I is suiliciently increased to restore the normal length of the bellows I and thus restore the valve mechanism I to its normal or neutral condition in which neither of the pipes I and I is in communication with the motive fluid supply pipe I", or is open to exhaust. Valve mechanism operations which are the reverse of those just described are produced by a decrease in the control pressure transmitted to the bellows I by the pipe H.

For its operative eifect on the valve mechanism I, only a very slight movement of the end wall of the bellows I from its normal position is required, and the normal position of the bellows end wall is the same for all values of the control pressure in the bellows 1 The position of the piston I and of the damper B thus varies with, and corresponds in a predetermined manner to the different values of the control pressure in pipe H. As will be apparent, the apparatus shown in Fig. 1, can be so designed and adjusted as to keep the pressure in the chamber a within a range so small, that, from the practical furnace operation standpoint, the pressure may be regarded as practically constant. While the par ticular form of regulator I shown is well adapted for its use illustrated in Fig. 1, that particular form of regulator constitutes no part of the present invention, and hence need not be explained herein. It is noted, however, that the regulator I comprises novel features of construction and arrangement which is fully disclosed in an application Serial Number 137,247 filed April 16, 1937 by Coleman B. Moore who invented that regulator.

As hereinafter explained, the instrument FA shown in Fig. 2 is of a commercial type differing from that of the instrument F of Fig. 1, but includes all of the features of the instrument F to which reference has been made heretofore. In respect to those features, Fig. 2 may be regarded as a more detailed illustration of the instru ment F. Thus, the latter may include in lieu of the simple lever I shown in Fig. l, a lever like the lever FA of Fig. 2, which is fulcrumed by means of a knife-edge pivot FA. The lever FA also includes an adjustable arm FA formed with an elongated slot in which is clamped a part FA, adjustable longitudinally of the slot, and to which the lower end of the link F is pivoted. As shown, the adjustable counterweight FA. of Fig. 2 diners inform and disposition from the counterweight F of Fig. 1. As indicated in Fig. 2, the fulcrum pivot F for the lever element F is carried by a lever F The permanently positioned pivot axis for the latter may be and as shown in Fig. 2, is

coincident with that of the pivotal connection F between the link F and member F when the latter is in the neutral position shown in Fig. 2.

The lever F may be angularly adjusted to thereby adjustthe pivot F, by manual adjustment of an adjusting device F of known form. Each of the instruments F and FA include a pen-arm F adjusted about the said permanent axis of the lever F by the up and down movements of the link F which turn the lever F" about itsfulcrum pivot F Fig. 2 shows the usual electric instruclosed in the Coleman B. Moore, Patent No. 2,125,081,.granted July 26, 1938. The air controller mechanism of the instruments F and FA may be either of the types respectively employed in the Full Throttlor, and. Air-O-Line controller instruments, manufactured and sold by the Brown Instrument Company, the common assignee of myself and the said Moore. The Full Throttlor controller includes mechanism, indicated in Fig. 1, but which need'not be described, through which on each initial adjustment of the flapper valve F, a relatively quick partial return or follow-up adjustment of the flapper F is effected, by pneumatic mechanism producing a corresponding adjustment of the pivot F for the flapper valve actuating lever F The Air-O-Line type of controller shown in Fig. 2, includes means generally similar to those of the instrument F for effecting follow-up adjustments, and also include provisions for effecting a subsequent delayed compensating" or reset adjustment of the pivot F more or less completely neutralizing the preceding followup adjustment. The purpose and effect-of the means for effecting such follow-up and compensating adjustment are now well known and need not be described herein. The Air-O-Line type of instrument shown in Fig. 2, also includes adjustment features indicated in Fig. 2, which while desirable in such instruments, need not be described herein.

While the special Full Throttlor and Air-O- Line controller features just referred to, include nothing claimed as novel herein, and are not necessarily used in the practice of the invention claimed herein, a reference to those features is appropriate herein, because they are illustrative of the fact, that in the combinations herein claimed, use may be made of commercially successful air controller instruments of different types. Furthermore, the simple pressure responsive controller combinations in which those air controller mechanism features are included in accordance with the present invention, permit full advantage to be taken of the inherent accuracy, sensitivity, and capacity for adjustment of said mechanisms. Existing and commercially successful aircontroller instruments including those mechanisms may be converted into my improved pressure responsive controllers, without reconstruction, and by the addition of parts which may readily be mounted within the existing instrument casings.

The instrument FB shown in Fig. 3 includes air controller mechanism fb which may, and as shown, is of a type which does, include the common features of the air controller mechanisms f and fa of the instruments F and FA. The instrument FB, however, includes a pressure gauge element, mounted within the casing of the instrument and analogous to that included in the device D of Fig. 1. The said gauge of the instrument FB, comprises, a container DA for sealing liquid, into which depends a bell member D surrounding an uprising extension CA of a pipe through which the furnace or other controlling pressure is transmitted to the instrument. DA is a gauge calibrating element of known form, adapted for use in establishing theproper height of sealing liquid level in the container DA.

The bell D is suspended from a lever F through an uprising stem connection D having atransversely bent upper end portion carrying a'depending pivot D which bears against and engages the bottom wall of a bearing cavity formed in a bearing part F carried by the lever F The oscillations of lever F give up and down movements to a link F serving the same purpose as the link F of the instruments F and FA. The lower end of the link F is pivoted to a lever F between the fulcrum pivot F for the lever and its connection by a link F, to an adjustable portion F of the lever F The lever F serves the purposes of the lever F of the instruments F and FA. The lever F carries an adjustable counterweight F and a pointer F connected to the lever F indicates the value of the controlling pressure in the upper portion of the bell D on a suitable scale F The instrument FB may be used in lieu of the instrument F and device D in such a furnace pressure control arrangement as is shown in Fig. 1.

As will be apparent without further explanation, the general pressure responsive, air controller action of the instrument F3, is like that of each of the instruments FA and F. Insofar as concerns the regulation of the control pressure in the pipe H, the effect of the vertical adjustment of the bell D of the instrument FB, may be identical with the effect of the vertical adjustments of the receiver armature i of the instruments F or FA. In each form of instrument, the linkage connection between the instrument, actuating member, D or i, and the biased flapper valve F, is of a character to practically eliminate all lost motion, and to make frictional resistance insignificant from the practical standpoint. Furthermore, in the instrument FB, as in the instruments F and FA, the instrument means by which the actuating element, D or z, is vertically adjusted, act on the actuating element without interference due to lost motion or friction. that in the instrument FB, the sealing liquid imposes a resistance which is, or is analogous to, frictional resistance, to movement of the bell D relative. to the liquid, but that resistance, while tending to slightly slow down the movements of the bell in response to quick changes in the pressure transmitted to its interior by the pipe CA does not interfere with the precise changes in the vertical position of the bell, which are intended to result from changes in the pressure transmitted to the interior of the bell. The mechanical and operative simplicity of the means provided in the instruments F, FA and F3, for making the air controller mechanism of each instrument properly responsive to small changes in a small furnace or other controlling pressure, will be plainly apparent to those skilled in the art.

Having now described my invention, what I claim as new and desire to secure by Letters Patent-is:

1. In a pressure responsive air controller instrument, the combination of an air controller mechanism including an adjustable bleeder valve element, a lever, rigid parts pivotally connected to form a non-elastic linkage connection between said lever and said element through which angular adjustments of the lever effect adjustments of said element, a member suspended by gravity from said lever, and means operating without substantial interference due to friction or lost motion on said' member, when subjected to It is true, of course,

an actuating force, to vertically adjust said memher to different positions in correspondence with the different values 01' said force, and adapted 2,223,356 force varying in" to be actuated by an actuating accordance with the changes in'a controlling pressure transmitted to said instrument from 'a 7 pressure source at a distance, from the instru'-* ment.

mechanism including an adjustable bleeder valve element, a lever, rigidparts pivotally connected to form anon-elastic'linkage connection be-' tween said lever and said element through which angular adjustments of; the lever efiect adjustments of said element, and a pressure gauge com prising a bell member suspended from said lever, a container for sealing bell depends, and controlling pressure transmitting means including into said bell member and opening into-the latter above the sealing liquid.

3. tion with means responsive to a pressure to be controlled and a regulator controlling said pressure, of an air controller instrument comprising an air controller mechanism including an adjustable bleeder valve element, a lever, rigid parts pivotally connected to form a non-elastic linkage connection between said lever and said element through which angular adjustments of the lever eflect adjustments of said element, a member suspended by'gravity from said lever, means operating without substantial friction or lost moliquid into which said a p p portion extending- In a pressure control system, the combination onsaid member, when subjected to an actuating force, to vertically adjust said member .to definite-positions in correspondence with the difl'erent values of said force, means cooperating with the first mentioned means to subject said member to an actuating force varying in correspondence with said pressure,

aerating with said bleedervalve element to trans- -mit to'said regulator a variable air pressure for actuating said regulator in accordance with the adjustments of said bleeder valve element.

4, An air controller instrument, comprising an 1 air controller mechanism including an adjustand means coopable bleeder valve element, a lever, rigid parts pivotally connected to form a non-elastic linkage connection between said lever and said element through which angular adjustments of the lever effect adjustments of said element, and an inductance bridge receiver comprising an armature suspended from said lever and end to end solenoid coils in which said armature is axially movable, an inductance bridge transmitter comprising an armature and end to solenoid coils in which the lastmentioned armature is axially movable, bridge conductors connecting the vtransmitter and receiver coils, bridge energizing means, and means for vertically adjusting the last mentioned armature in accordance with changes in a variable pressure.

ANKER. E. KROGH. 

